1. Field of the Invention
This invention relates to a pulse forming and delivery system and, more particularly, to a method and an apparatus for selectively forming and delivering a pulse of electrical energy to a flashlamp, effective to cause the flashlamp to radiate light for a predetermined period of time.
2. Description of the Prior Art
Pulse forming and delivery systems are normally used in combination with a laser flashlamp and are effective to deliver a pulse of electrical energy to the lamp, in order to allow the lamp to radiate light for a predetermined period of time.
Many of these prior systems employ a capacitor and inductor, which were arranged to receive an electrical current and to properly form or shape the received current into a pulse, before inputting the shaped pulse to the flashlamp. This prior capacitor-inductor arrangement is very inflexible since there was only a single capactive and inductive value that produces a properly dampened pulse having the desired width and energy. This arrangement is therefore very inflexible since it requires a substitution of the capacitor and/or inductor elements everytime a different type of pulses is desired.
Moreover, these prior systems also have great difficulty in producing very wide square pulses. That is, to produce these types of pulses, these prior pulse delivery systems require several meshes of capacitors and inductors in order to achieve the needed overall inductive valve. This mesh arrangement not only results in high resistive loss, but is also relatively costly and prone to failure. Moreover, this prior mesh arrangement is also relatively inflexible and requires modification everytime the desired pulse width was to be changed.
Other types of prior pulse forming and delivery systems utilize a transistor arrangement in which many transistors are connected in parallel fashion in order to provide the necessary pulse shaping. These prior systems effectively form pulses having only a limited range of widths and do not allow for much variation in the widths of the formed pulses. Additionally, these prior transistor systems were also relatively inefficient, costly, and prone to failure.
Further, all of these prior pulse forming and delivery systems also normally employ a closed loop control technique which constantly measures the pulse energy emanating from the flashlamp, compares this measured value with a previously determined optimal value, and modifies the amount of energy delivered to the pulse forming and delivery system based upon this comparison. This feedback arrangement has been found to be inaccurate due to the inherent and compounded inaccuracy of the energy delivery modification. Moreover, this arrangement has also been found to be prone to failure and to be inefficient.